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July Discobs 2019


George BM
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Heavy rain incoming this evening?

https://www.wpc.ncep.noaa.gov/metwatch/metwatch_mpd_multi.php?md=553&yr=2019

 

Mesoscale Precipitation Discussion 0553
NWS Weather Prediction Center College Park MD
600 PM EDT Sat Jul 06 2019

Areas affected...Central and Northern Mid-Atlantic

Concerning...Heavy rainfall...Flash flooding likely

Valid 062200Z - 070300Z

SUMMARY...Bands of showers and thunderstorms will focus across the
Mid-Atlantic region over the next few hours, with impacts expected
for the Philadelphia, Baltimore and Washington D.C. metropolitan
areas and adjacent suburbs involving the I-95 corridor. Flash
flooding is likely, and especially around the urban centers.

DISCUSSION...The latest radar and satellite imagery shows multiple
bands of heavy showers and thunderstorms advancing southeast
across southwest and central PA out ahead of a cold front.
Meanwhile, separate smaller clusters of convection are seen over
portions of southeast PA. The activity ahead of the cold front is
encountering a very moist and moderately unstable airmass that is
characterized by PWATs of 1.75 to 2 inches, and MLCAPE values of
1500+ j/kg. This very favorable thermodynamic environment coupled
with diffluent flow aloft around the south side of a flat upper
trough advancing across the Northeast.

However, the convection impacting areas of southeast PA is largely
attributed to locally enhanced surface convergence around the west
side of a convectively induced cold pool and associated outflow
boundary. This boundary extends from central NJ southwest across
the western suburbs of the Philadelphia metropolitan area and down
to near the Baltimore metropolitan area. The airmass from central
and northeast MD up across southeast PA is very unstable and
extremely moist with MLCAPE values of 2000 to 3000 j/kg, surface
dewpoints in the mid 70s, and overall PWATs of 2.0 to 2.25 inches.
The latest visible satellite imagery has been showing an axis of
agitated CU persisting near this boundary and certainly taking
advantage of very strong thermodynamics.

Over the next few hours, the more organized convective line
dropping southeast across southwest and central PA will encounter
this strong instability and extremely moist environment closer in
to the I-95 corridor and the adjacent western suburbs of
Philadelphia, Baltimore and Washington D.C. This coupled with the
aforementioned outflow boundary/cold pool situation will likely
allow for numerous clusters of very heavy showers and
thunderstorms to impact a large area of eastern and southeast PA,
down to areas of northeast and central MD going in closer to 00Z,
with development also possible across northern VA and around the
Washington D.C. metropolitan area. In fact, the low-level wind
field has been slowly backing over the last few hours along the
I-95 corridor and east of the Blue Ridge, which is not only
pooling stronger thermodynamics across the region, but also
facilitating greater surface convergence downstream of the cold
front as the leeside trough refocuses farther back to the west and
closer to the Blue Ridge.

The latest hires model suite of guidance including the HRRR favor
as much as 2 to 4 inches of rain locally through mid evening, of
which a large amount of that will be capable of falling in just an
hour or two. Flash flooding will be likely as a result, with the
threat enhanced especially across the urbanized I-95 corridor and
adjacent suburbia.

Orrison

ATTN...WFO...BGM...CTP...LWX...OKX...PHI...

ATTN...RFC...MARFC...NERFC...
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7 minutes ago, losetoa6 said:

Cecil county line I assume your talking about...looks decent 

Yes, that is correct.

But, the latest radar look seems to indicate the line is fading a bit. Still should get some rain though. 

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Special Weather Statement
National Weather Service Mount Holly NJ
823 PM EDT Sat Jul 6 2019

DEZ001-MDZ008-012-015-NJZ009-015>017-PAZ070-071-102-104>106-070115-
New Castle-Queen
Anne`s-Cecil-Kent-Salem-Mercer-Hunterdon-Gloucester-Lower
Bucks-Eastern Montgomery-Philadelphia-Upper Bucks-Delaware-Eastern
Chester-
823 PM EDT Sat Jul 6 2019

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT NEW CASTLE...NORTH
CENTRAL QUEEN ANNE`S...KENT...EASTERN CECIL...NORTHWESTERN MERCER...
NORTHWESTERN SALEM...SOUTH CENTRAL HUNTERDON...NORTHWESTERN
GLOUCESTER...SOUTHEASTERN MONTGOMERY...CENTRAL BUCKS...SOUTHEASTERN
CHESTER...PHILADELPHIA AND DELAWARE COUNTIES...

At 822 PM EDT, radar indicated strong thunderstorms were located
along a line extending from near Tinicum to Lima to near Betterton.
Movement was south at 20 mph.

Wind gusts up to 40 mph and pea size hail are possible with these
storms.

Locations impacted include...
Philadelphia, Camden, Wilmington, Newark, Middletown, Elkton,
Norristown, Chester, Lansdale, West Norriton, East Norriton,
Pennsville, Yeadon, Doylestown, Byram, Carneys Point, Conshohocken,
Hatboro, Folcroft and Ambler.
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45 minutes ago, frd said:

The storm cluster moving SE into the Northern Chessy Bay look to be getting stronger. Forming a line at this time at the

leading edge. Boaters beware !   

Winds jumped from 5mph to 31 mph in approximately 90 seconds.  Of course this was probably 7 minutes after watching a pontoon boat w/ over five people on it, bugging out of the creek headed for the river... 

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3 minutes ago, MN Transplant said:

4”/hr rain rate, but it doesn’t add up when it only lasts a minute or two.  Lightning show is good.  No wind.

Yeah, you got the fatter part of the line.  Looks like a swath of 0.5”+ between Mattie and I, pointed in your direction.

if you want some model fun, go check out the end of the 00z HRRR.  Completely rakes FFX and Loudoun tomorrow night.

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6 minutes ago, mattie g said:

And about a minute of rain followed by maybe another 30 seconds.

But the kids certainly heard the thunder because wife and I are both in different rooms helping them get back to sleep. Argh!!!!

My daughter fell asleep during the fireworks last night (edit-Thursday, time gets away from me).  She is the true “sleep through a freight train” kid.  Other faults, but at least we got that going for us.

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Yeah, you got the fatter part of the line.  Looks like a swath of 0.5”+ between Mattie and I, pointed in your direction.
if you want some model fun, go check out the end of the 00z HRRR.  Completely rakes FFX and Loudoun tomorrow night.


Man, you’ve been getting screwed. Past couple of storms have been some of the more energetic ones I’ve seen in awhile. Lots of good T&L lately.
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